1. Field of the Invention
The present invention relates to a mobile terminal apparatus (in this specification it may be also called simply a terminal in the present specification) such as cellular phone devices and a Personal Digital Assistants (PDAs).
2. Description of Related Art
Mobile terminal apparatuses such as a cellular phone and a personal digital assistant (PDA) may to be lost or stolen because of their portability. When a mobile terminal apparatus storing personal information such as telephone book data, memo data, and electronic mail (email) data is stolen or lost, data including the personal information may be improperly accessed or altered.
Although attempts have been made for assuring security against unauthorized access to data in a terminal when necessary through the introduction of various types of authentication methods, the conventional authentication method is not necessarily effective considering the importance of personal information.
Japanese Patent Publication No. 2001-309431 discloses a technology in which, when a notification indicating that a mobile terminal apparatus is lost is sent to the location registration center of the mobile terminal apparatus, the location registration center causes a base station to send a control signal to the mobile terminal apparatus to disable its key operation when the mobile terminal apparatus communicates with the base station and, after transferring internal data to the database of the location registration center, causes the mobile terminal apparatus to erase the data.